First record in Africa of the parasitoid Dolichogenidea gelechiidivoris (Hymenoptera: Braconidae) on tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae) from tomato fields in Algeria

The Neotropical parasitoid wasp Dolichogenidea gelechiidivoris (Marsh, 1975) (Hymenoptera: Braconidae), one of the most important biocontrol agents of the South American tomato pinworm Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), is reported for the first time from Africa, from tomato grown in open fields and greenhouses in several regions of Algeria. Color photos of specimens from Algeria, Spain and South America, as well as the holotype and one paratype are provided. Morphological and molecular details to better characterize and recognize the species are also provided. We speculate that D. gelechiidivoris arrived accidentally to Algeria from Spain, where it has recently been reported. The consequences for future biocontrol projects against T. absoluta in Africa are discussed.

Comprehensive Metabolome and Volatilome Analyses in Eggplant and Tomato Reveal Their Differential Responses to Tuta absoluta Infestation

The South American tomato pinworm, Tuta absoluta, is one of the most destructive insect pests in Solanaceae crops, particularly in tomatoes. Current methods of management have proven somewhat effective but still require a more efficacious management strategy to limit its havoc on crop yield. Tomato is much more predisposed to T. absoluta as compared with other plants such as eggplants, but the underlying causes have not been fully determined. We conducted this study to unravel the volatile organic compounds (VOCs) and primary/secondary metabolites that account for the differential response of tomatoes and eggplants to T. absoluta infestation. We performed widely targeted comparative metabolome and volatilome profiling by ultraperformance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) and headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry (HS-SPME/GC-MS), respectively, on eggplants and tomatoes under control and T. absoluta infestation conditions. Overall, 141 VOCs and 797 primary/secondary metabolites were identified, largely dominated by aldehyde, alcohols, alkanes, amine, aromatics, a heterocyclic compound, ketone, olefin, phenol, and terpenes. Most of the VOCs and primary/secondary metabolites from the terpene class were largely differentially regulated in eggplants compared with tomatoes. Eggplants emitted several compounds that were lower or completely absent in tomatoes either under control conditions or after T. absoluta infestation. The results from an electroantennogram showed that 35 differentially accumulated VOCs could elicit female T. absoluta response, implying that these volatile compounds significantly alter the behavior of this pest. These findings demonstrated that differentially accumulated metabolites and volatile compounds play major roles in eggplant resistance to T. absoluta infestation as these compounds were regulated upon attack by T. absoluta. Our findings can assist in integrated pest management efforts by developing appropriate control measures against T. absoluta in Solanaceae production.

Biological invasion risk assessment of Tuta absoluta: mechanistic versus correlative methods

The capacity to assess invasion risk from potential crop pests before invasion of new regions globally would be invaluable, but this requires the ability to predict accurately their potential geographic range and relative abundance in novel areas. This may be unachievable using de facto standard correlative methods as shown for the South American tomato pinworm Tuta absoluta, a serious insect pest of tomato native to South America. Its global invasive potential was not identified until after rapid invasion of Europe, followed by Africa and parts of Asia where it has become a major food security problem on solanaceous crops. Early prospective assessment of its potential range is possible using physiologically based demographic modeling that would have identified knowledge gaps in T. absoluta biology at low temperatures. Physiologically based demographic models (PBDMs) realistically capture the weather-driven biology in a mechanistic way allowing evaluation of invasive risk in novel areas and climes including climate change. PBDMs explain the biological bases for the geographic distribution, are generally applicable to species of any taxa, are not limited to terrestrial ecosystems, and hence can be extended to support ecological risk modeling in aquatic ecosystems. PBDMs address a lack of unified general methods for assessing and managing invasive species that has limited invasion biology from becoming a more predictive science.

Supercooling capacity and cold tolerance of the South American tomato pinworm, Tuta absoluta, a newly invaded pest in China

Tuta absoluta is a devastating invasive pest worldwide, causing severe damage to the global tomato industry. It has been recorded recently in the northwestern border areas of China, posing a significant threat to tomato production. It was presumed that the region's winter-related low temperatures would avert the alien species from successfully overwintering. In this study, the supercooling capacity and low-temperature tolerance of this pest were examined under laboratory conditions and its overwintering potential in Xinjiang was estimated. The results showed that the lowest supercooling point was recorded in the adult stage (− 19.47 °C), while the highest (− 18.11 °C) was recorded in the pupal stage. The supercooling points of pupae and adults were not influenced by gender. The Ltemp50 and Ltemp90 of female and male adults were the lowest when exposed to cold for 2 h. However, when the duration of exposure extended from 4 to 10 h, the Ltemp50 and Ltemp90 of female and male pupae were the lowest. Comparison of the lowest Ltemp50 and Ltemp90 with temperatures in January indicated that T. absoluta might not be able to overwinter in most of the northern and central regions of Xinjiang. However, in the southern regions, the extremely low temperature was higher than the Ltemp90, suggesting that T. absoluta has a higher overwintering potential in these regions. These results form a basis for predicting the dispersal potential and possible geographic range of this pest in Xinjiang. In addition, our findings provide guidance for the control of this pest by reducing overwintering shelters.

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) on the “Offensive” in Africa: Prospects for Integrated Management Initiatives

The South American tomato pinworm Tuta absoluta (Meyrick) has aggressively invaded the African continent. Since its first detection in North Africa in Morocco and Tunisia in 2008, it has successfully invaded the entire southern, eastern and western Africa, where it has been on the offensive, causing significant damage to Solanaceous food crops. While control of this prolific invader is primarily based on conventional synthetic pesticides, this form of control is consistently losing societal approval owing to (1) pesticide resistance development and consequential loss of field efficacy; (2) growing public health concerns; (3) environmental contamination and loss of biological diversity and its associated ecological services; and (4) unsustainable costs, particularly for resource-poor African farmers. As such, more ecologically sound pest management strategies, e.g., the use of natural substances (NSs), may offer a more sustainable approach to tackling this offensive. A systematic literature search through digital libraries and online databases (JSTOR, PubMed, Web of Science, SCOPUS and Google Scholar) was conducted using predetermined keywords on T. absoluta, e.g., South American tomato pinworm. We use this to explain the invasion of T. absoluta in Africa, citing mechanisms facilitating African invasion and exploring the potential of its control using diverse biological control agents, natural and low-risk substances. Specifically, we explore how botanicals, entomopathogens, semiochemicals, predators, parasitoids, host plant resistance, sterile insect technique and others have been spatially employed to control T. absoluta and discuss the potential of these control agents in African landscapes using more integrated approaches. We discuss the use of NSs as assets to general insect pest control, some potential associated liabilities and explain the potential use and barriers to adoption in African systems from a legislative, economic, ecological and social standpoint.